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The VAAI dead space reclamation primitive is integrated into the array through the SCSI protocol. Depending on the version of ESXi the host is running, the primitive can automatically reclaim space.
VMFS-6 and ESXi versions that support automatic UNMAP: The best practice is to keep or reduce the reclamation rate to the Low or 100 MB/s, which is the default setting (see the following figure).
Note: vSphere 8 introduces the ability to configure the space reclamation rate to as low as 10 MB/s. This can be useful for environments where space reclamation at a higher rate can be disruptive to the storage fabric or its consumers.
VMFS-5 and ESXi versions that do not support automatic UNMAP: The best practice is to set the reclamation rate to 200.
esxcli storage vmfs unmap --volume-label=volume_label --reclaim-unit=200
Note: In certain older versions of ESXi, you must manually invoke the dead space reclamation primitive. See the VMware Knowledge Base for more information about which versions require additional steps.